Mitsubishi Delica Owners Club UK™

[andyman]

Has anyone bought and fitted new bearing caps on their existing 4d56's camshaft? After the timing belt snapped, it wasn't the rockers or camshaft that broke, it was the bearing caps, around the threaded holes for the rocker shaft mountings. Camshaft, freed of rockers, rotated very smoothly, with no apparent play in the existing plain bearing caps.
So Q1) : If I order new bearing caps from any of the many online sites, how can I be sure they will be machined to the correct tolerances, as no sizes are given? Are they all machined to + d from an absolute standard size? You wouldn't expect that from crank journals, or pistons! Or is the expectation that you buy a complete, built up head, so all parts are machined to fit each other perfectly? In which case, why would they sell the bearing caps separately?
As all valves appear to be fully shut (only checked with a straight edge across the tops of the valve stems,) it is looking promising that with a diesel compression gauge, and all plugs out, with  the gauge screwed in when that piston is at BDC, I should be able to  turn the crankshaft 180deg with a spanner, and get a reliable enough reading, hopefully between the acceptable parameters 384 - 440psi.
Q2) Am I correct in this assumption, or is it true, as a self-professed expert has told me, that too much pressure/air will leak away in a single, manual turn, (obviously repeating the process for each cylinder) so the only way to check and compare compression is to rebuild the valve gear, with new belts and correct timing, so that the engine can be spun on the starter to minimise compression leak, and establish a maximum, and comparable pressure for each cylinder in this way? Definitive answers, with reasoning only, please, or links to authoritative articles only, please!    
PS, Happy New Year all!
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Andy C L300 Super Exceed - over 100 smiles per gallon!

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